Soldering Made Easy

Tips & Techniques

Learning to solder is easy, inexpensive and can save both money and frustration. PAUL WHITE makes it as painless as possible -- just as long as you pick up the soldering iron by the right end!

It's probably true to say that soldering pieces of wire to plugs is just about as exciting as mowing the lawn, but unless you're prepared to spend an absolute fortune on ready-made leads, it's a skill well worth acquiring. Fortunately, the knack of soldering is quickly picked up, and the necessary equipment costs so little that you'll probably break even after making your first half-dozen leads.

HOW IT'S DONE

It's very tempting to try to heat up a blob of solder on the end of the soldering iron and then carry it to where it's needed, but this is absolutely the wrong approach and will leave you with dry joints -- dry joint being a term for a joint which is both electrically and mechanically dubious.

The right way to solder is as follows:

 After ensuring that the end of the soldering iron bit is filed flat (especially necessary if the iron has been resting at the bottom of a tool box for ten years), plug it in and allow it to heat up. Melt a little solder on the tip of the iron and wipe off the excess with a piece of rag. This is known as 'tinning the iron'.

 Strip the wire to be soldered and twist the end. Hold the tip of the soldering iron against the wire and then feed in a little fresh solder between the bit and the wire. The solder should flow onto the wire and penetrate the spaces between the individual wires, creating a single, stiff conductor.

 Next tin the tag inside the plug you are wiring in exactly the same way. If the solder blocks the hole in the tag, heat it up again and quickly bang the plug on a hard surface. The excess solder should fall off before it hardens, so don't do this over anything valuable!

 Using the pliers, push the tinned end of the wire through the hole in the tag and then wrap it around the tag once using the pliers. Ideally, you should have a reasonable mechanical joint before you solder the two parts together, though with some types of plug, you have no choice but to rely on the solder to hold the wire to its destination.

 Place the soldering iron bit against the joint and feed in a little fresh solder. Keep the iron in place until the solder flows smoothly between the wire and the tag. If it refuses to flow or forms reluctant blobs, heat the joint up again and apply more fresh solder. The fresh solder is important because it is the chemical flux inside the solder that cleans the joint and makes the solder flow.

 In the event that you fabricate a porcine auditory organ out of the whole thing, don't despair; pull the joint apart, strip the wire back a bit further, clean the excess solder off the tags and have another go. Within half an hour you'll be soldering like a professional.

WHAT YOU NEED

The ideal soldering iron for wiring is between 20 and 40 watts; suitable models can be bought from Tandy or Maplin for just a few pounds. You'll also need a reel of Multicore solder (solder with the flux already in it), a small pair of pliers and a pair of wire cutters. Wire strippers are also useful -- if you strip the wire with your cutters, you stand a good chance of cutting right through it by accident. Other than that, all you need is an old file or some wet and dry paper to clean up the end of end of the soldering iron bit (the hot thing sticking out of the soldering iron) and a piece of rag to wipe off excess solder.

TIPS

Most soldering jobs appear to need three hands. Life can be made much easier if you fix an ordinary wooden clothes peg in a vice and use the peg to hold the component you are soldering (you can also get small, purpose-built soldering stations that serve the same purpose – look in the Maplin catalogue). Alternatively, in the case of jack plugs, you can simply fit the plug into any convenient jack socket while you work on it. Come to think of it, the same is true of most audio connectors, such as DINs, phonos and XLRs. However, if the type of plug so dictates, make sure that the cover of the plug is threaded on the cable before you solder the lead to the plug. This sounds so obvious, but after more years than I care to remember soldering my own leads, I still find myself forgetting it!